public class Example03 {
    public static void main(String[] args) {
        String str = "abcd";
        System.out.println("将字符串转为字符数组后的结果：");
        char[] charArray = str.toCharArray();
        for (int i = 0; i < charArray.length; i++) {
            if(i !=charArray.length-1 ){
                System.out.println(charArray[i]+",");
            }else {
                System.out.println(charArray[i]);
            }

        }
        System.out.println("将int值转换为string类型之后的结果："+String.valueOf(12));
        System.out.println("将字符串转换为大写的结果："+str.toUpperCase());
        System.out.println("将字符串转换为小写的结果："+str.toLowerCase());
    }
}
